Moderator

Tess Thompson - Associate Professor - Virginia Tech

S2.1 - Nature-based solutions to promote water circularity in the industrial sector

The management of the various industrial effluents represents one of the greatest challenges not only for the industrial sector but generally for the water sector. Industrial wastewaters can have a large variety of sources, physico-chemical composition and pollutants nature, based on the industrial process and the raw materials/chemicals used. This is why they are more complex than municipal ones, which makes it more difficult to develop effective management solutions. Industrial wastewaters are characterized by high organic load, low biodegradability, high solids and nutrients content, potential presence of toxic compounds, pollutants variety, intense colour, high turbidity and salinity, extreme pH values and fluctuations in flow rates, loads and composition, among others. At the same time, there is a growing need for sustainable solutions, i.e., to find attractive alternatives over conventional technologies with reduced operation costs, reduced external energy input and minimized environmental footprint. To this, many industries have introduced Corporate Social Responsibility concerns in their strategic management aiming at contributing to environmental protection, besides the desire to improve their financial position. The wastewater treatment strategy can be an essential tool for advancing operations and improving corporate financial performance. Especially in low income regions, the need for cost-effective and financially feasible solutions is imperative. In this context, the use of nature-based solutions such as the green technology of Constructed Wetlands is gaining increasing global attention and popularity. Over the last years, there is a gradual increase of studies and applications of constructed wetlands for various industries. This technology carries the main properties that fulfil the above criteria such as few mechanical parts, limited maintenance needs, limited or even no need for specialized staff, minimized use of non-renewable materials (concrete, steel etc.), design flexibility and replicability, reduced greenhouse gas emissions, minimum energy consumption, and no harmful by-products. Furthermore, the use of nature-based solutions for wastewater management enables the reuse of the treated effluents, e.g., for irrigation of crops or recycling back in the industrial process, closing this way the loop of water and promoting circularity aspects and practices in the industry. The goal of this study is to present two examples from the Middle East region where nature-based solutions have been applied under warm and arid climate for the treatment and reuse of two different industrial effluents. The first example comes from Iran and a glass manufacturing industry, where a constructed wetland system treats the process effluent and the treated water is recirculated and reused in the glass manufacturing process. The second example comes from Oman and focuses on the oil industry, where the oil recovery by-product (oily wastewater) is treated in a large constructed wetland system and the treated effluent is reused onsite for irrigation of crops with market value, while other by-products (reeds biomass) are tested for compost production and biogas generation.

Speaker

Alexandros Stefanakis - Assistant Professor - Technical University of Crete

S2.2 - Introducing green technologies for wastewater treatment and reuse for agricultural irrigation – effects on soil and crops

Green technologies (GreenT) such as high rate algae ponds, evapotranspirative willow systems, and constructed wetlands enable recovery of water and nutrients from municipal wastewater (WW) along with production of valuable by-products like biomass or bio-stimulants to increase crop production while treating WW. In this study three pilot GreenT for treatment of mechanically pre-treated municipal WW were compared, namely (1) high rate algal pond (HRAP) for production of algae biomass and treated water for irrigation; (2) evapotranspirative willow system (EWS) with zero outflow for production of wood biomass; and (3) constructed wetland (CW) for production of reed biomass and treated water for irrigation. Pilot GreenT were monitored for one vegetative season for WW treatment efficiency and biomass production (algae and wood). Treated water was used for irrigation of pumpkin plants in lysimeter tests. Basic WW parameters were measured at the inflow and outflow of pilot GreenT, algal biomass production was monitored with Chlorophyll-a analyses and through the volume of produced sludge and its TSS, while wood biomass was measured through weighting the trees from EWS at coppicing. Lysimeter water outflow, irrigation water consumption and pumpkin plant growth were monitored continuously. Targeted pollutants were measured in lysimeter soil and pumpkin tissues (roots, stems & leaves and fruits). HRAP was operating under two hydraulic retention times, namely 10 and 5 days. After reducing the retention time bacterial community slowly began to dominate the algal community, which was shown as a decrease in chlorophyll a concentration. Removal of BOD5 was high at both retention times, while COD removal was low at 10-day retention time and increased when bacteria started to prevail. HRAP also showed efficient removal of PO4-P; however, the removal of nitrogen compounds was not consistent. CW showed efficient removal of TSS, BOD5 and COD despite it was the first year of its operation. Removal of PO4-P was minimal and removal of NH4-N only appeared in the second half of vegetation season. The EWS was evaluated according to water balance which showed that willow can evapotranspire from 1200 to 1500 mm of water per year resulting in 40-50 m2 of system needed to treated WW of 1 PE. According to biomass production EWS can produce 140-170 kg of wood biomass per PE per year and HRAP produce 73-146 kg of algae biomass. During vegetative season pumpkin plants were irrigated with 1.8-4 l of wastewater per plant regarding weather conditions and corresponding evapotranspiration. Lysimeter test included 28 pumpkin plants that produced 42 pumpkins with a total yield of 139 kg. Laboratory analysis showed normal or just slight increased nutrient values compared to Slovenian regulation for the quality of agricultural soils. Plant tissues are being analysed and results will also be presented at the conference. The obtain results will help to evaluate and optimize selected GreenT for WW treatment to obtain safe end products for agricultural uses regarding systems efficiency, while addressing environmental benefits and health risks.

Speaker

Tjasa Griessler Bulc - Full professor/Senior researcher - University of Ljubljana

S2.3 - The Waterharmonica, over 20 years experience with Reuse of waste water through natural processes

The Waterharmonica is a successful water innovation in The Netherlands, with over 17 full scale applications for ecological upgrading of 1000 – 40.000 m3/per day treated waste water, with a some more under design. The first years between 1995 and 2005 most were aimed on nutrient removal, buffering water and supply of water for agriculture. Most of the recent Waterharmonica’s are focusing on creating natural values, fish spawning and migration and on natural processes for water reuse as recreational waters The Waterharmonica is a (natural) constructed wetland as well an ecological engineering solution for upgrading well treated waste water with relative low carbon loads. It is a special combination through of a customized selection of constructed natural processes for: biological filtration by Daphnia, phototrophic processes in algae mats on reed stems, oxygenation during day time by water plants, introducing food chains, ecotoxicological aspects, natural and recreational values, water buffering, nutrient removal, etc. The presentation will give an overview of our wide experience on Waterharmonica systems in the Netherlands during the last two decades: both practical experiences and results of research on nutrient removal, the reduction of suspended particles, largely by biological filtration of particles from and algae by Daphnia, disinfection, the processes of turning the treated waste water into a more natural type of water, fish spawning, ecotoxicological aspects, etc.. Attention will be given to cost and revenues, to recreation, spatial planning and the Waterharmonica as an example of Ecosystem engineering, like ‘Empuriabrava’ (Costa Brava, Spain), effluent polishing in constructed wetlands, wetland to accept tertiary treated wastewater (United States) and constructed wetlands for secondary effluent treatment and water reuse (Australia). The Waterharmonica concept is not only about ecological engineering, or wetland processes. The catchy name does promote wetlands in a positive way, providing a natural link between the ‘water chain’ from potable water, sewerage, waste water treatment to the ‘water system’ with rivers and lakes, including landscaping and recreation. The current generation of multifunctional Waterharmonicas developed to a circular economy and product development, a source for a useful, clear, living water, even low in nutrients and of a good (eco)toxical quality: Ecoservice systems.

Speaker

Ruud Kampf - Independent consultant, retired - Rekel/water and Rekel Kenya Ltd